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Antarctic Tectonics: Constraints From an ERS-1 Satellite Marine Gravity Field
1D. McAdoo is with the Geosciences Laboratory, National Ocean Service, National Oceanic and Atmospheric Administration, Silver Spring, MD 20910, USA. S. Laxon is with Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London, Dorking, Surrey RH5 6NT, UK.
Abstract:
A high-resolution gravity field of poorly charted and ice-covered ocean near West Antarctica, from the Ross Sea east to the Weddell Sea, has been derived with the use of satellite altimetry, including ERS-1 geodetic phase, wave-form data. This gravity field reveals regional tectonic fabric, such as gravity lineations, which are the expression of fracture zones left by early (65 to 83 million years ago) Pacific-Antarctic sea-floor spreading that separated the Campbell Plateau and New Zealand continent from West Antarctica. These lineations constrain plate motion history and confirm the hypothesis that Antarctica behaved as two distinct plates, separated from each other by an extensional Bellingshausen plate boundary active in the Amundsen Sea before about 61 million years ago.